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Polyimide(PI) has be taken greater use in the aerospace and civil area due to its excellent performance. Researchers have acquired some achievements when mixing PI and some inorganic materials such SiO2, TiO2 into hybrid materials. In this paper, we employ3,3’,4,4’-benzophenonetetracarboxylic dianhydride(BTDA), and 3, 4,3’,4’-biphenyl dianhydride (s-BPDA) as a dianhydride monomer, use 4,4’-diaminodiphenyl ether (ODA) as a diamine monomer. Then ultrasonic dispersion and situ polymerization were taken to compound a series of Polyamic acid precursor doped with TiO2 nanotubes and multi-walled carbon nanotubes (MWNTs). Finally, we obtained the polyimide composite by pouring hot imidization on Polyamic acid precursor. Related works is as follows.1 PI(BTDA-ODA)/SiO2 nanoparticle thin film is prepared. The structure, morphology and properties of coextruded film were characterized by using FT-IR, UV-vis, XRD, SEM, TGA, TEM, DMA and so on. The influences of nanoparticles content on conductivity of composite films were investigated by measuring the resistance of composite films. The results show that imidization of the film was completely and there some bonding between SiO2 nano-particles and PI matrix, which affect the order degree of original PI molecular chain. The nano-particles dispersed uniformly. We can see that with the increase of the content of SiO2 nanoparticles, the particle size increases, the film light transmittance reduces, thermal stability increased, the volume resistivity of films increases, the dielectric constant reduced, the glass transition temperature improves.2 PI(BTDA-ODA)/TiO2 nanotube thin film is prepared. The structure, morphology and properties of composite film were characterized by using FT-IR, UV-vis, XRD, TEM, TGA and so on. The results show that imidization of the film was completely. TiO2 nanotubes and PI matrix is cross-linked and constitute the network, which affect the order degree of original PI molecular chain. The nano-particles dispersed uniformly. We can see that with the increase of the content of TiO2 nanoparticles, the particle size increases, the film light transmittance reduces, thermal stability increased.3 PI(s-BPDA-ODA)/MWNTs film is prepared:Using mixed acid and thionyl chloride separately to modify the characteristic MWNTs, which solves the problem that the carbon nanotubes are easy to be a bundle and cannot be dissolve in organic solvents, and improves its compatibility with Polyimide substrate, which makes it homogeneously dispersed in the composite film. The structure, morphology and properties of carbon nanotubes and composite film both before and after modified were characterized by using XPS、NMR、FT-IR、UV-vis、XRD、SEM、TGA、TEM、DMA and so on. The influences of nanotubes content on conductivity of composite films were investigated by measuring the resistance of composite films. The results show that the addition of MWNTs has no significant effect on the chemical structure of polyimide matrix, which maintains a good heat resistance of matrix. By observing the water absorption of composite films, with the increase of carbon content, water absorption rate of the volume of composite films gradually increases. By comparing the resistivity of composite films with different carbon content, with the increase of carbon content, the conductivity of composite films has been greatly improved.The Polyimide nanocomposites prepared above have excellent thermal properties, mechanical properties and electrical properties, which is expected to be more widely used in the area engineering plastics and aerospace.
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